net/ipv4/inet_connection_sock.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Support for INET connection oriented protocols.
   7  *
   8  * Authors:     See the TCP sources
   9  *
  10  *              This program is free software; you can redistribute it and/or
  11  *              modify it under the terms of the GNU General Public License
  12  *              as published by the Free Software Foundation; either version
  13  *              2 of the License, or(at your option) any later version.
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/jhash.h>
  18
  19 #include <net/inet_connection_sock.h>
  20 #include <net/inet_hashtables.h>
  21 #include <net/inet_timewait_sock.h>
  22 #include <net/ip.h>
  23 #include <net/route.h>
  24 #include <net/tcp_states.h>
  25 #include <net/xfrm.h>
  26
  27 #ifdef INET_CSK_DEBUG
  28 const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
  29 EXPORT_SYMBOL(inet_csk_timer_bug_msg);
  30 #endif
  31
  32 /*
  33  * This struct holds the first and last local port number.
  34  */
  35 struct local_ports sysctl_local_ports __read_mostly = {
  36         .lock = __SEQLOCK_UNLOCKED(sysctl_local_ports.lock),
  37         .range = { 32768, 61000 },
  38 };
  39
  40 unsigned long *sysctl_local_reserved_ports;
  41 EXPORT_SYMBOL(sysctl_local_reserved_ports);
  42
  43 void inet_get_local_port_range(int *low, int *high)
  44 {
  45         unsigned int seq;
  46
  47         do {
  48                 seq = read_seqbegin(&sysctl_local_ports.lock);
  49
  50                 *low = sysctl_local_ports.range[0];
  51                 *high = sysctl_local_ports.range[1];
  52         } while (read_seqretry(&sysctl_local_ports.lock, seq));
  53 }
  54 EXPORT_SYMBOL(inet_get_local_port_range);
  55
  56 int inet_csk_bind_conflict(const struct sock *sk,
  57                            const struct inet_bind_bucket *tb, bool relax)
  58 {
  59         struct sock *sk2;
  60         struct hlist_node *node;
  61         int reuse = sk->sk_reuse;
  62
  63         /*
  64          * Unlike other sk lookup places we do not check
  65          * for sk_net here, since _all_ the socks listed
  66          * in tb->owners list belong to the same net - the
  67          * one this bucket belongs to.
  68          */
  69
  70         sk_for_each_bound(sk2, node, &tb->owners) {
  71                 if (sk != sk2 &&
  72                     !inet_v6_ipv6only(sk2) &&
  73                     (!sk->sk_bound_dev_if ||
  74                      !sk2->sk_bound_dev_if ||
  75                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
  76                         if (!reuse || !sk2->sk_reuse ||
  77                             sk2->sk_state == TCP_LISTEN) {
  78                                 const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
  79                                 if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
  80                                     sk2_rcv_saddr == sk_rcv_saddr(sk))
  81                                         break;
  82                         }
  83                         if (!relax && reuse && sk2->sk_reuse &&
  84                             sk2->sk_state != TCP_LISTEN) {
  85                                 const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
  86
  87                                 if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
  88                                     sk2_rcv_saddr == sk_rcv_saddr(sk))
  89                                         break;
  90                         }
  91                 }
  92         }
  93         return node != NULL;
  94 }
  95 EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);
  96
  97 /* Obtain a reference to a local port for the given sock,
  98  * if snum is zero it means select any available local port.
  99  */
 100 int inet_csk_get_port(struct sock *sk, unsigned short snum)
 101 {
 102         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 103         struct inet_bind_hashbucket *head;
 104         struct hlist_node *node;
 105         struct inet_bind_bucket *tb;
 106         int ret, attempts = 5;
 107         struct net *net = sock_net(sk);
 108         int smallest_size = -1, smallest_rover;
 109
 110         local_bh_disable();
 111         if (!snum) {
 112                 int remaining, rover, low, high;
 113
 114 again:
 115                 inet_get_local_port_range(&low, &high);
 116                 remaining = (high - low) + 1;
 117                 smallest_rover = rover = net_random() % remaining + low;
 118
 119                 smallest_size = -1;
 120                 do {
 121                         if (inet_is_reserved_local_port(rover))
 122                                 goto next_nolock;
 123                         head = &hashinfo->bhash[inet_bhashfn(net, rover,
 124                                         hashinfo->bhash_size)];
 125                         spin_lock(&head->lock);
 126                         inet_bind_bucket_for_each(tb, node, &head->chain)
 127                                 if (net_eq(ib_net(tb), net) && tb->port == rover) {
 128                                         if (tb->fastreuse > 0 &&
 129                                             sk->sk_reuse &&
 130                                             sk->sk_state != TCP_LISTEN &&
 131                                             (tb->num_owners < smallest_size || smallest_size == -1)) {
 132                                                 smallest_size = tb->num_owners;
 133                                                 smallest_rover = rover;
 134                                                 if (atomic_read(&hashinfo->bsockets) > (high - low) + 1 &&
 135                                                     !inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, false)) {
 136                                                         snum = smallest_rover;
 137                                                         goto tb_found;
 138                                                 }
 139                                         }
 140                                         if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, false)) {
 141                                                 snum = rover;
 142                                                 goto tb_found;
 143                                         }
 144                                         goto next;
 145                                 }
 146                         break;
 147                 next:
 148                         spin_unlock(&head->lock);
 149                 next_nolock:
 150                         if (++rover > high)
 151                                 rover = low;
 152                 } while (--remaining > 0);
 153
 154                 /* Exhausted local port range during search?  It is not
 155                  * possible for us to be holding one of the bind hash
 156                  * locks if this test triggers, because if 'remaining'
 157                  * drops to zero, we broke out of the do/while loop at
 158                  * the top level, not from the 'break;' statement.
 159                  */
 160                 ret = 1;
 161                 if (remaining <= 0) {
 162                         if (smallest_size != -1) {
 163                                 snum = smallest_rover;
 164                                 goto have_snum;
 165                         }
 166                         goto fail;
 167                 }
 168                 /* OK, here is the one we will use.  HEAD is
 169                  * non-NULL and we hold it's mutex.
 170                  */
 171                 snum = rover;
 172         } else {
 173 have_snum:
 174                 head = &hashinfo->bhash[inet_bhashfn(net, snum,
 175                                 hashinfo->bhash_size)];
 176                 spin_lock(&head->lock);
 177                 inet_bind_bucket_for_each(tb, node, &head->chain)
 178                         if (net_eq(ib_net(tb), net) && tb->port == snum)
 179                                 goto tb_found;
 180         }
 181         tb = NULL;
 182         goto tb_not_found;
 183 tb_found:
 184         if (!hlist_empty(&tb->owners)) {
 185                 if (sk->sk_reuse == SK_FORCE_REUSE)
 186                         goto success;
 187
 188                 if (tb->fastreuse > 0 &&
 189                     sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
 190                     smallest_size == -1) {
 191                         goto success;
 192                 } else {
 193                         ret = 1;
 194                         if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, true)) {
 195                                 if (sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
 196                                     smallest_size != -1 && --attempts >= 0) {
 197                                         spin_unlock(&head->lock);
 198                                         goto again;
 199                                 }
 200
 201                                 goto fail_unlock;
 202                         }
 203                 }
 204         }
 205 tb_not_found:
 206         ret = 1;
 207         if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep,
 208                                         net, head, snum)) == NULL)
 209                 goto fail_unlock;
 210         if (hlist_empty(&tb->owners)) {
 211                 if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
 212                         tb->fastreuse = 1;
 213                 else
 214                         tb->fastreuse = 0;
 215         } else if (tb->fastreuse &&
 216                    (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
 217                 tb->fastreuse = 0;
 218 success:
 219         if (!inet_csk(sk)->icsk_bind_hash)
 220                 inet_bind_hash(sk, tb, snum);
 221         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 222         ret = 0;
 223
 224 fail_unlock:
 225         spin_unlock(&head->lock);
 226 fail:
 227         local_bh_enable();
 228         return ret;
 229 }
 230 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 231
 232 /*
 233  * Wait for an incoming connection, avoid race conditions. This must be called
 234  * with the socket locked.
 235  */
 236 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 237 {
 238         struct inet_connection_sock *icsk = inet_csk(sk);
 239         DEFINE_WAIT(wait);
 240         int err;
 241
 242         /*
 243          * True wake-one mechanism for incoming connections: only
 244          * one process gets woken up, not the 'whole herd'.
 245          * Since we do not 'race & poll' for established sockets
 246          * anymore, the common case will execute the loop only once.
 247          *
 248          * Subtle issue: "add_wait_queue_exclusive()" will be added
 249          * after any current non-exclusive waiters, and we know that
 250          * it will always _stay_ after any new non-exclusive waiters
 251          * because all non-exclusive waiters are added at the
 252          * beginning of the wait-queue. As such, it's ok to "drop"
 253          * our exclusiveness temporarily when we get woken up without
 254          * having to remove and re-insert us on the wait queue.
 255          */
 256         for (;;) {
 257                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 258                                           TASK_INTERRUPTIBLE);
 259                 release_sock(sk);
 260                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 261                         timeo = schedule_timeout(timeo);
 262                 lock_sock(sk);
 263                 err = 0;
 264                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 265                         break;
 266                 err = -EINVAL;
 267                 if (sk->sk_state != TCP_LISTEN)
 268                         break;
 269                 err = sock_intr_errno(timeo);
 270                 if (signal_pending(current))
 271                         break;
 272                 err = -EAGAIN;
 273                 if (!timeo)
 274                         break;
 275         }
 276         finish_wait(sk_sleep(sk), &wait);
 277         return err;
 278 }
 279
 280 /*
 281  * This will accept the next outstanding connection.
 282  */
 283 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 284 {
 285         struct inet_connection_sock *icsk = inet_csk(sk);
 286         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 287         struct sock *newsk;
 288         struct request_sock *req;
 289         int error;
 290
 291         lock_sock(sk);
 292
 293         /* We need to make sure that this socket is listening,
 294          * and that it has something pending.
 295          */
 296         error = -EINVAL;
 297         if (sk->sk_state != TCP_LISTEN)
 298                 goto out_err;
 299
 300         /* Find already established connection */
 301         if (reqsk_queue_empty(queue)) {
 302                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 303
 304                 /* If this is a non blocking socket don't sleep */
 305                 error = -EAGAIN;
 306                 if (!timeo)
 307                         goto out_err;
 308
 309                 error = inet_csk_wait_for_connect(sk, timeo);
 310                 if (error)
 311                         goto out_err;
 312         }
 313         req = reqsk_queue_remove(queue);
 314         newsk = req->sk;
 315
 316         sk_acceptq_removed(sk);
 317         if (sk->sk_protocol == IPPROTO_TCP && queue->fastopenq != NULL) {
 318                 spin_lock_bh(&queue->fastopenq->lock);
 319                 if (tcp_rsk(req)->listener) {
 320                         /* We are still waiting for the final ACK from 3WHS
 321                          * so can't free req now. Instead, we set req->sk to
 322                          * NULL to signify that the child socket is taken
 323                          * so reqsk_fastopen_remove() will free the req
 324                          * when 3WHS finishes (or is aborted).
 325                          */
 326                         req->sk = NULL;
 327                         req = NULL;
 328                 }
 329                 spin_unlock_bh(&queue->fastopenq->lock);
 330         }
 331 out:
 332         release_sock(sk);
 333         if (req)
 334                 __reqsk_free(req);
 335         return newsk;
 336 out_err:
 337         newsk = NULL;
 338         req = NULL;
 339         *err = error;
 340         goto out;
 341 }
 342 EXPORT_SYMBOL(inet_csk_accept);
 343
 344 /*
 345  * Using different timers for retransmit, delayed acks and probes
 346  * We may wish use just one timer maintaining a list of expire jiffies
 347  * to optimize.
 348  */
 349 void inet_csk_init_xmit_timers(struct sock *sk,
 350                                void (*retransmit_handler)(unsigned long),
 351                                void (*delack_handler)(unsigned long),
 352                                void (*keepalive_handler)(unsigned long))
 353 {
 354         struct inet_connection_sock *icsk = inet_csk(sk);
 355
 356         setup_timer(&icsk->icsk_retransmit_timer, retransmit_handler,
 357                         (unsigned long)sk);
 358         setup_timer(&icsk->icsk_delack_timer, delack_handler,
 359                         (unsigned long)sk);
 360         setup_timer(&sk->sk_timer, keepalive_handler, (unsigned long)sk);
 361         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 362 }
 363 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 364
 365 void inet_csk_clear_xmit_timers(struct sock *sk)
 366 {
 367         struct inet_connection_sock *icsk = inet_csk(sk);
 368
 369         icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
 370
 371         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 372         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 373         sk_stop_timer(sk, &sk->sk_timer);
 374 }
 375 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 376
 377 void inet_csk_delete_keepalive_timer(struct sock *sk)
 378 {
 379         sk_stop_timer(sk, &sk->sk_timer);
 380 }
 381 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 382
 383 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 384 {
 385         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 386 }
 387 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 388
 389 struct dst_entry *inet_csk_route_req(struct sock *sk,
 390                                      struct flowi4 *fl4,
 391                                      const struct request_sock *req)
 392 {
 393         struct rtable *rt;
 394         const struct inet_request_sock *ireq = inet_rsk(req);
 395         struct ip_options_rcu *opt = inet_rsk(req)->opt;
 396         struct net *net = sock_net(sk);
 397         int flags = inet_sk_flowi_flags(sk);
 398
 399         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
 400                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 401                            sk->sk_protocol,
 402                            flags,
 403                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->rmt_addr,
 404                            ireq->loc_addr, ireq->rmt_port, inet_sk(sk)->inet_sport);
 405         security_req_classify_flow(req, flowi4_to_flowi(fl4));
 406         rt = ip_route_output_flow(net, fl4, sk);
 407         if (IS_ERR(rt))
 408                 goto no_route;
 409         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 410                 goto route_err;
 411         return &rt->dst;
 412
 413 route_err:
 414         ip_rt_put(rt);
 415 no_route:
 416         IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
 417         return NULL;
 418 }
 419 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 420
 421 struct dst_entry *inet_csk_route_child_sock(struct sock *sk,
 422                                             struct sock *newsk,
 423                                             const struct request_sock *req)
 424 {
 425         const struct inet_request_sock *ireq = inet_rsk(req);
 426         struct inet_sock *newinet = inet_sk(newsk);
 427         struct ip_options_rcu *opt;
 428         struct net *net = sock_net(sk);
 429         struct flowi4 *fl4;
 430         struct rtable *rt;
 431
 432         fl4 = &newinet->cork.fl.u.ip4;
 433
 434         rcu_read_lock();
 435         opt = rcu_dereference(newinet->inet_opt);
 436         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
 437                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 438                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 439                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->rmt_addr,
 440                            ireq->loc_addr, ireq->rmt_port, inet_sk(sk)->inet_sport);
 441         security_req_classify_flow(req, flowi4_to_flowi(fl4));
 442         rt = ip_route_output_flow(net, fl4, sk);
 443         if (IS_ERR(rt))
 444                 goto no_route;
 445         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 446                 goto route_err;
 447         rcu_read_unlock();
 448         return &rt->dst;
 449
 450 route_err:
 451         ip_rt_put(rt);
 452 no_route:
 453         rcu_read_unlock();
 454         IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
 455         return NULL;
 456 }
 457 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 458
 459 static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
 460                                  const u32 rnd, const u32 synq_hsize)
 461 {
 462         return jhash_2words((__force u32)raddr, (__force u32)rport, rnd) & (synq_hsize - 1);
 463 }
 464
 465 #if IS_ENABLED(CONFIG_IPV6)
 466 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
 467 #else
 468 #define AF_INET_FAMILY(fam) 1
 469 #endif
 470
 471 struct request_sock *inet_csk_search_req(const struct sock *sk,
 472                                          struct request_sock ***prevp,
 473                                          const __be16 rport, const __be32 raddr,
 474                                          const __be32 laddr)
 475 {
 476         const struct inet_connection_sock *icsk = inet_csk(sk);
 477         struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
 478         struct request_sock *req, **prev;
 479
 480         for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
 481                                                     lopt->nr_table_entries)];
 482              (req = *prev) != NULL;
 483              prev = &req->dl_next) {
 484                 const struct inet_request_sock *ireq = inet_rsk(req);
 485
 486                 if (ireq->rmt_port == rport &&
 487                     ireq->rmt_addr == raddr &&
 488                     ireq->loc_addr == laddr &&
 489                     AF_INET_FAMILY(req->rsk_ops->family)) {
 490                         WARN_ON(req->sk);
 491                         *prevp = prev;
 492                         break;
 493                 }
 494         }
 495
 496         return req;
 497 }
 498 EXPORT_SYMBOL_GPL(inet_csk_search_req);
 499
 500 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
 501                                    unsigned long timeout)
 502 {
 503         struct inet_connection_sock *icsk = inet_csk(sk);
 504         struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
 505         const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
 506                                      lopt->hash_rnd, lopt->nr_table_entries);
 507
 508         reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
 509         inet_csk_reqsk_queue_added(sk, timeout);
 510 }
 511 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
 512
 513 /* Only thing we need from tcp.h */
 514 extern int sysctl_tcp_synack_retries;
 515
 516
 517 /* Decide when to expire the request and when to resend SYN-ACK */
 518 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
 519                                   const int max_retries,
 520                                   const u8 rskq_defer_accept,
 521                                   int *expire, int *resend)
 522 {
 523         if (!rskq_defer_accept) {
 524                 *expire = req->num_timeout >= thresh;
 525                 *resend = 1;
 526                 return;
 527         }
 528         *expire = req->num_timeout >= thresh &&
 529                   (!inet_rsk(req)->acked || req->num_timeout >= max_retries);
 530         /*
 531          * Do not resend while waiting for data after ACK,
 532          * start to resend on end of deferring period to give
 533          * last chance for data or ACK to create established socket.
 534          */
 535         *resend = !inet_rsk(req)->acked ||
 536                   req->num_timeout >= rskq_defer_accept - 1;
 537 }
 538
 539 int inet_rtx_syn_ack(struct sock *parent, struct request_sock *req)
 540 {
 541         int err = req->rsk_ops->rtx_syn_ack(parent, req, NULL);
 542
 543         if (!err)
 544                 req->num_retrans++;
 545         return err;
 546 }
 547 EXPORT_SYMBOL(inet_rtx_syn_ack);
 548
 549 void inet_csk_reqsk_queue_prune(struct sock *parent,
 550                                 const unsigned long interval,
 551                                 const unsigned long timeout,
 552                                 const unsigned long max_rto)
 553 {
 554         struct inet_connection_sock *icsk = inet_csk(parent);
 555         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 556         struct listen_sock *lopt = queue->listen_opt;
 557         int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
 558         int thresh = max_retries;
 559         unsigned long now = jiffies;
 560         struct request_sock **reqp, *req;
 561         int i, budget;
 562
 563         if (lopt == NULL || lopt->qlen == 0)
 564                 return;
 565
 566         /* Normally all the openreqs are young and become mature
 567          * (i.e. converted to established socket) for first timeout.
 568          * If synack was not acknowledged for 1 second, it means
 569          * one of the following things: synack was lost, ack was lost,
 570          * rtt is high or nobody planned to ack (i.e. synflood).
 571          * When server is a bit loaded, queue is populated with old
 572          * open requests, reducing effective size of queue.
 573          * When server is well loaded, queue size reduces to zero
 574          * after several minutes of work. It is not synflood,
 575          * it is normal operation. The solution is pruning
 576          * too old entries overriding normal timeout, when
 577          * situation becomes dangerous.
 578          *
 579          * Essentially, we reserve half of room for young
 580          * embrions; and abort old ones without pity, if old
 581          * ones are about to clog our table.
 582          */
 583         if (lopt->qlen>>(lopt->max_qlen_log-1)) {
 584                 int young = (lopt->qlen_young<<1);
 585
 586                 while (thresh > 2) {
 587                         if (lopt->qlen < young)
 588                                 break;
 589                         thresh--;
 590                         young <<= 1;
 591                 }
 592         }
 593
 594         if (queue->rskq_defer_accept)
 595                 max_retries = queue->rskq_defer_accept;
 596
 597         budget = 2 * (lopt->nr_table_entries / (timeout / interval));
 598         i = lopt->clock_hand;
 599
 600         do {
 601                 reqp=&lopt->syn_table[i];
 602                 while ((req = *reqp) != NULL) {
 603                         if (time_after_eq(now, req->expires)) {
 604                                 int expire = 0, resend = 0;
 605
 606                                 syn_ack_recalc(req, thresh, max_retries,
 607                                                queue->rskq_defer_accept,
 608                                                &expire, &resend);
 609                                 req->rsk_ops->syn_ack_timeout(parent, req);
 610                                 if (!expire &&
 611                                     (!resend ||
 612                                      !inet_rtx_syn_ack(parent, req) ||
 613                                      inet_rsk(req)->acked)) {
 614                                         unsigned long timeo;
 615
 616                                         if (req->num_timeout++ == 0)
 617                                                 lopt->qlen_young--;
 618                                         timeo = min(timeout << req->num_timeout,
 619                                                     max_rto);
 620                                         req->expires = now + timeo;
 621                                         reqp = &req->dl_next;
 622                                         continue;
 623                                 }
 624
 625                                 /* Drop this request */
 626                                 inet_csk_reqsk_queue_unlink(parent, req, reqp);
 627                                 reqsk_queue_removed(queue, req);
 628                                 reqsk_free(req);
 629                                 continue;
 630                         }
 631                         reqp = &req->dl_next;
 632                 }
 633
 634                 i = (i + 1) & (lopt->nr_table_entries - 1);
 635
 636         } while (--budget > 0);
 637
 638         lopt->clock_hand = i;
 639
 640         if (lopt->qlen)
 641                 inet_csk_reset_keepalive_timer(parent, interval);
 642 }
 643 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
 644
 645 /**
 646  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
 647  *      @sk: the socket to clone
 648  *      @req: request_sock
 649  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 650  *
 651  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
 652  */
 653 struct sock *inet_csk_clone_lock(const struct sock *sk,
 654                                  const struct request_sock *req,
 655                                  const gfp_t priority)
 656 {
 657         struct sock *newsk = sk_clone_lock(sk, priority);
 658
 659         if (newsk != NULL) {
 660                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 661
 662                 newsk->sk_state = TCP_SYN_RECV;
 663                 newicsk->icsk_bind_hash = NULL;
 664
 665                 inet_sk(newsk)->inet_dport = inet_rsk(req)->rmt_port;
 666                 inet_sk(newsk)->inet_num = ntohs(inet_rsk(req)->loc_port);
 667                 inet_sk(newsk)->inet_sport = inet_rsk(req)->loc_port;
 668                 newsk->sk_write_space = sk_stream_write_space;
 669
 670                 newicsk->icsk_retransmits = 0;
 671                 newicsk->icsk_backoff     = 0;
 672                 newicsk->icsk_probes_out  = 0;
 673
 674                 /* Deinitialize accept_queue to trap illegal accesses. */
 675                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
 676
 677                 security_inet_csk_clone(newsk, req);
 678         }
 679         return newsk;
 680 }
 681 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
 682
 683 /*
 684  * At this point, there should be no process reference to this
 685  * socket, and thus no user references at all.  Therefore we
 686  * can assume the socket waitqueue is inactive and nobody will
 687  * try to jump onto it.
 688  */
 689 void inet_csk_destroy_sock(struct sock *sk)
 690 {
 691         WARN_ON(sk->sk_state != TCP_CLOSE);
 692         WARN_ON(!sock_flag(sk, SOCK_DEAD));
 693
 694         /* It cannot be in hash table! */
 695         WARN_ON(!sk_unhashed(sk));
 696
 697         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
 698         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
 699
 700         sk->sk_prot->destroy(sk);
 701
 702         sk_stream_kill_queues(sk);
 703
 704         xfrm_sk_free_policy(sk);
 705
 706         sk_refcnt_debug_release(sk);
 707
 708         percpu_counter_dec(sk->sk_prot->orphan_count);
 709         sock_put(sk);
 710 }
 711 EXPORT_SYMBOL(inet_csk_destroy_sock);
 712
 713 int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
 714 {
 715         struct inet_sock *inet = inet_sk(sk);
 716         struct inet_connection_sock *icsk = inet_csk(sk);
 717         int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
 718
 719         if (rc != 0)
 720                 return rc;
 721
 722         sk->sk_max_ack_backlog = 0;
 723         sk->sk_ack_backlog = 0;
 724         inet_csk_delack_init(sk);
 725
 726         /* There is race window here: we announce ourselves listening,
 727          * but this transition is still not validated by get_port().
 728          * It is OK, because this socket enters to hash table only
 729          * after validation is complete.
 730          */
 731         sk->sk_state = TCP_LISTEN;
 732         if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
 733                 inet->inet_sport = htons(inet->inet_num);
 734
 735                 sk_dst_reset(sk);
 736                 sk->sk_prot->hash(sk);
 737
 738                 return 0;
 739         }
 740
 741         sk->sk_state = TCP_CLOSE;
 742         __reqsk_queue_destroy(&icsk->icsk_accept_queue);
 743         return -EADDRINUSE;
 744 }
 745 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
 746
 747 /*
 748  *      This routine closes sockets which have been at least partially
 749  *      opened, but not yet accepted.
 750  */
 751 void inet_csk_listen_stop(struct sock *sk)
 752 {
 753         struct inet_connection_sock *icsk = inet_csk(sk);
 754         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 755         struct request_sock *acc_req;
 756         struct request_sock *req;
 757
 758         inet_csk_delete_keepalive_timer(sk);
 759
 760         /* make all the listen_opt local to us */
 761         acc_req = reqsk_queue_yank_acceptq(queue);
 762
 763         /* Following specs, it would be better either to send FIN
 764          * (and enter FIN-WAIT-1, it is normal close)
 765          * or to send active reset (abort).
 766          * Certainly, it is pretty dangerous while synflood, but it is
 767          * bad justification for our negligence 8)
 768          * To be honest, we are not able to make either
 769          * of the variants now.                 --ANK
 770          */
 771         reqsk_queue_destroy(queue);
 772
 773         while ((req = acc_req) != NULL) {
 774                 struct sock *child = req->sk;
 775
 776                 acc_req = req->dl_next;
 777
 778                 local_bh_disable();
 779                 bh_lock_sock(child);
 780                 WARN_ON(sock_owned_by_user(child));
 781                 sock_hold(child);
 782
 783                 sk->sk_prot->disconnect(child, O_NONBLOCK);
 784
 785                 sock_orphan(child);
 786
 787                 percpu_counter_inc(sk->sk_prot->orphan_count);
 788
 789                 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->listener) {
 790                         BUG_ON(tcp_sk(child)->fastopen_rsk != req);
 791                         BUG_ON(sk != tcp_rsk(req)->listener);
 792
 793                         /* Paranoid, to prevent race condition if
 794                          * an inbound pkt destined for child is
 795                          * blocked by sock lock in tcp_v4_rcv().
 796                          * Also to satisfy an assertion in
 797                          * tcp_v4_destroy_sock().
 798                          */
 799                         tcp_sk(child)->fastopen_rsk = NULL;
 800                         sock_put(sk);
 801                 }
 802                 inet_csk_destroy_sock(child);
 803
 804                 bh_unlock_sock(child);
 805                 local_bh_enable();
 806                 sock_put(child);
 807
 808                 sk_acceptq_removed(sk);
 809                 __reqsk_free(req);
 810         }
 811         if (queue->fastopenq != NULL) {
 812                 /* Free all the reqs queued in rskq_rst_head. */
 813                 spin_lock_bh(&queue->fastopenq->lock);
 814                 acc_req = queue->fastopenq->rskq_rst_head;
 815                 queue->fastopenq->rskq_rst_head = NULL;
 816                 spin_unlock_bh(&queue->fastopenq->lock);
 817                 while ((req = acc_req) != NULL) {
 818                         acc_req = req->dl_next;
 819                         __reqsk_free(req);
 820                 }
 821         }
 822         WARN_ON(sk->sk_ack_backlog);
 823 }
 824 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
 825
 826 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
 827 {
 828         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
 829         const struct inet_sock *inet = inet_sk(sk);
 830
 831         sin->sin_family         = AF_INET;
 832         sin->sin_addr.s_addr    = inet->inet_daddr;
 833         sin->sin_port           = inet->inet_dport;
 834 }
 835 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
 836
 837 #ifdef CONFIG_COMPAT
 838 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
 839                                char __user *optval, int __user *optlen)
 840 {
 841         const struct inet_connection_sock *icsk = inet_csk(sk);
 842
 843         if (icsk->icsk_af_ops->compat_getsockopt != NULL)
 844                 return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
 845                                                             optval, optlen);
 846         return icsk->icsk_af_ops->getsockopt(sk, level, optname,
 847                                              optval, optlen);
 848 }
 849 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
 850
 851 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
 852                                char __user *optval, unsigned int optlen)
 853 {
 854         const struct inet_connection_sock *icsk = inet_csk(sk);
 855
 856         if (icsk->icsk_af_ops->compat_setsockopt != NULL)
 857                 return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
 858                                                             optval, optlen);
 859         return icsk->icsk_af_ops->setsockopt(sk, level, optname,
 860                                              optval, optlen);
 861 }
 862 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
 863 #endif
 864
 865 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
 866 {
 867         const struct inet_sock *inet = inet_sk(sk);
 868         const struct ip_options_rcu *inet_opt;
 869         __be32 daddr = inet->inet_daddr;
 870         struct flowi4 *fl4;
 871         struct rtable *rt;
 872
 873         rcu_read_lock();
 874         inet_opt = rcu_dereference(inet->inet_opt);
 875         if (inet_opt && inet_opt->opt.srr)
 876                 daddr = inet_opt->opt.faddr;
 877         fl4 = &fl->u.ip4;
 878         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
 879                                    inet->inet_saddr, inet->inet_dport,
 880                                    inet->inet_sport, sk->sk_protocol,
 881                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
 882         if (IS_ERR(rt))
 883                 rt = NULL;
 884         if (rt)
 885                 sk_setup_caps(sk, &rt->dst);
 886         rcu_read_unlock();
 887
 888         return &rt->dst;
 889 }
 890
 891 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
 892 {
 893         struct dst_entry *dst = __sk_dst_check(sk, 0);
 894         struct inet_sock *inet = inet_sk(sk);
 895
 896         if (!dst) {
 897                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
 898                 if (!dst)
 899                         goto out;
 900         }
 901         dst->ops->update_pmtu(dst, sk, NULL, mtu);
 902
 903         dst = __sk_dst_check(sk, 0);
 904         if (!dst)
 905                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
 906 out:
 907         return dst;
 908 }
 909 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);